Hydraulic cylinder that will automatically expunge air and self level

ABSTRACT

A hydraulic cylinder with piston and rod enclosed, that upon receiving air and oil, singularly or along with one or more identical cylinders, from a new, dry, system start up, will, upon extension, when the piston seal passes a predetermined point, stop. With continued pumping from either a manual single or multiple cylinder pump or an electric pump all the identical piston rods will arrive at the predetermined stop and the cylinders will be purged of air and when the manual locks are placed over the extended piston rods, they will stay there and not move up or down, regardless of ambient temperature changes or inadvertent release of the oil. After they are extended the first time all the cylinders will stop at the predetermined point in an even position with each other. The locks and pumps are not shown in this application.

BACKGROUND OF THE INVENTION

Camping trailer roofs, truck body roofs, mobile housing roofs, truck camper roofs, pickup truck caps, work trailers, work tables, boat lifts and the like have long been provided with lifting mechanisms. Of those requiring an absolute level top, when raised few have used hydraulic systems because of the expense and unreliability of electronic and mechanical stops and valves and because of the movements caused by variations in the ambient temperatures and the variables of up to five percent when using flow controllers, flow dividers, geared apportioners and the like when eveness of minus one fourth inch is required.

SUMMARY

The present invention is a hydraulic cylinder with a piston and piston rod of the same diameter. The piston rod having grooves for wear rings and seals and grooves and holes to permit air and oil to move up the rod to a predetermined and precisely formed relief hole in the side of the cylinder tube which is connected thru the cylinder wall to a relief tube which runs down the outside of the cylinder tube and is connected to a system of hoses, connected to as many other cylinders identical to the one above as are used in the unit and connected to the return line to the reservoir so that when oil is pumped from any scource, either manual or electric pump, equipped with flow divider cartridges or flow controllers or apportioners into the bottom of the cylinders, the pistons will rise and when the piston seals pass above the relief hole, the roof will stop going up and the oil and air in the system will return to the reservoir with the air venting out and the system purged and ready to function and completely even. This assures that the surface being lifted by each cylinder finishes perfectly even with the surface being lifted by every other cylinder in the system regardless of the disparity of the heights of the tops of the piston rods on the way up. With the installation of the mechanical locks on the piston rods, the system, in conjunction with the relief holes will not move up or down regardless of ambient temperatures or the inadvertent release of the oil.

The difficulties of moving hydraulic seals past holes have long been known. The invention's unique method, which overcomes this problem has been tested intensely, without compromising the integrity of the system and will be shown in the drawings and described in the description of the drawings.

DESCRIPTION

While the invention may be susceptible to embodiment in different forms, there is shown in the drawings, and herein will be described in detail, specific embodiments with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that as illustrated and described herein.

The present invention, FIG. 1 provides a hydraulic cylinder 10 with a metal relief tube 12 exiting from the top at the side and running vertically down the side of the cylinder 10 past the bottom. A hydraulic supply hose 14 connected to a fitting 16 at the bottom of the cylinder. A relief hose 18 connecting to the bottom of the metal exterior relief tube 12 and connecting to the relief hoses 18 that run from the relief tubes 12 of however many additional, identical, cylinders 10 are used in the unit and also return the air and oil expeled from the cylinders 10 to the reservoir (not shown) when the piston seal 22 in FIG.2 is pushed past the relief hole 38 in FIG. 4. causing the top of the piston 20 to be level with the top of all the other pistons 20 who's seals 22 have passed the relief hole 38

FIG. 2 provides a one piece piston and rod 20 with a piston seal 22, a seal groove 24, a narrowed oil retaining area 26, and a grooved transfer channel 28 connecting the horizontal intersecting hole 30 to the narrowed oil retaining area 26, a groove for a wear ring 32, and wear ring 34.

FIG. 3 describes a vertical hole 36 in the bottom of the piston 20 intersecting the horizontal intersecting hole 30, so that oil entering the bottom of the cylinder 10 from the supply hose 14 under pressure, will enter hole 36 in the bottom of the piston 20, and exit hole 30, and rise thru the transfer channel 28 to the narrowed oil retaining area 26, putting pressure on the piston seal 22, causing the piston 20 to rise.

FIG. 4 describes a cylinder 10 with walls 40 wherein a piston 20 shown in FIG.2 resides. One wall 40 has a relief hole 38 connecting to the metal relief tube 12, with a precisely engineered approach 42, and a precisely engineered departure 44. So when the seal 22 on the piston 20 enters the relief hole 38 area, it will pass by and not be compromised or damage the integrity of the system. 

1. A hydraulic cylinder comprising a cylinder tube with an enclosed bottom end and a threaded hole in said bottom end to which a pressure line carrying fluid from a pressure scource is connected, said cylinder tube having on it's interior, vertical wall, at a predetermined and optional location near the top, a relief hole with a precisely engineered approach and a precisely engineered departure passing thru said interior, vertical wall, and opening into a relief tube attached to, and extending down the vertical exterior of said vertical wall to a point below the bottom of the said cylinder tube, said cylinder tube having in it's interior a single piece piston and rod combined, of the same diameter, with the lower portion serving as the piston, and the upper portion serving as the rod, said lower portion having a groove containing a wear ring, said lower portion has an interior opening, rising from the bottom center of the piston and intersecting with a horizontal opening entering the piston slightly above the said groove containing the wear ring, said outer opening of the horizontal opening, intersecting with a vertical transfer channel on the exterior of the piston rising to a narrowed oil retaining area of the piston, a groove containing a hydraulic seal at the upper edge of said narrowed oil retaining area, said seal causing the single piece piston and rod to extend when supplied with oil from a pressure source.
 2. A hydraulic cylinder as claimed in claim 1, with a single piece piston and rod of the same diameter, adjustable to stop at any desired, predetermined point upon receiving fluid.
 3. A hydraulic cylinder as claimed in claim 2, that along with one or more identical cylinders, will, upon receiving fluid arrive at a state of complete eveness of extension of all the pistons in the system if all are adjusted to the same predetermined point, regardless of the uneveness of the extension of the pistons enroute.
 4. A hydraulic cylinder as claimed in claim 1, that can be adjusted to easily and simply stop at a predetermined point without using complicated and unreliable electrical limit switches and mechanical devices, thereby eliminating over extensions and damaging canvas or other materials on the sides and ends of camping trailers and truck campers and any other collateral damage that may occur to the system it is being used in, or the surrounding area.
 5. A cylinder relief hole, so engineered as to permit a hydraulic seal on a piston, in a cylinder, to pass by thousands of cycles without compromising the seal or the integrity or function of the cylinder. 